Macrumors forum member michaelb, in a fit of jealousy over his ladyfriend's new unibody MacBook, decided to try to trick his last-gen MacBook Air into recognizing four-finger gestures. He installed the updated 10.5.5 system from the new MacBook onto his Air, and then through some tricky manipulation of the kernel extension, managed to get the flashy four-finger gestures working. This is like the invention of sliced bread times infinity. He can use Exposé and Application Switcher just like the newer models, and suspects all later-model MacBooks could also work. Macrumors warns that this is absolutely not recommended for the casual user, and could have awful results you and I can't even guess at, but it's definitely an impressive trick. Makes you wonder why Apple couldn't have just updated all of the older machines via a firmware upgrade, doesn't it? [Macrumors]
If Apple distributed a firmware update to allow older laptops to get new functionality like this, I bet they would have to charge for it again, under the Sarbanes-Oxley regulations, much like how they did when restrospectively adding 802.11n to some MacBooks and iMacs. Of course, then, you'd all be bitching to no end that you're being charged the astronomical sum of $5 or whatever to get functionality already supposedly built-in to your hardware.
News flash, folks. You got what you paid for. If you thought that the money you spent for your 1st Gen Air should have entitled you to use 4 finger gestures, then you shouldn't have bought it then. Even if the hardware could potentially do it, the R&D and programming required to make the hardware realize that potential happened after the fact, and Apple has no obligation to retrospectively make that new tech available for previous customers.
Is it greed? Sure, insofar as every, and I mean EVERY, corporation in our capitalist society is greedy by definition.
Frankly, having been primarily a Win/Tel laptop user before I became an Apple laptop user back in the day, I find it funny haters would be bitching about something like this, when it was commonplace (is it still?) for Windows laptops to not even let you upgrade your OS (e.g., from 98SE to 2000, or from 2000 to XP) without going the "unsupported, and you'll have to d/l, install, and maintain all updated drivers yourself" route.
Of course, I'm never against signs of altruism, so I'm not against Apple releasing such a firmware upgrade in the future (which they still may do, although I doubt it). I'd also like to know if there are any high-profile examples on the Windows side, by companies like Dell, HP, Sony, Acer, Asus, and Lenovo, who have done something similar—that is to say, to take new technologies that were developed *in-house* for their new laptops and make them available retrospectively to their older models. This cannot include simply firmware updates provided and distributed by third party hardware vendors, since making those available to users don't cost the PC vendors a single dime.